High temperature material



Dec. 8, 1959 s. VERNET ET AL HIGH TEMPERATURE MATERIAL Filed Ilay 18, 1956 INVENTORS M mm Mm R m N 6 A R V N S N! 0 F n a [A Th0 RMa U in 7 5J6 M United States Patent 6 Claims. (Cl. 73-3682) and George Asalrawa, by direct and mesne Yellow Springs, Ohio,

This invention relates to thermally expansible materials, and to power elements of the type disclosed in copending patent December 8, 1955 and Serial No. 510,708, filed on May 24, 1955. Such power elements are commonly employed to operate switches and valves.

Objects of the invention are to provide thermal expansion materials having relatively large total expansion and good resistance to chemical decomposition at their expansion temperatures.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

In the drawings:

The single figure is a sectional view through a power element incorporating the invention.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

In the drawings there is shown a power element 1 including a casing 2, a body or pellet of thermally expansible material 3, a movable wall or piston 4, a corrugated stainless steel diaphragm 5, and a body of pliable forcetransmitting material 6. Material 6 is preferably the pliable material disclosed in Serial No. 583,881, filed May 9, 1956, and now abandoned. A disc 7 of polytetrafluoroethylene is positioned between material 6 and piston 4 in order to prevent material 6 from extruding into the clearance space 9 between piston 4 and bore 8. A spring (not shown) is provided for returning piston 4 to its illustrated position during contractive movement of material 3.

Operation of the power element is such that during temperature increase in the ambient atmosphere, material 3 expands against diaphragm 5 so as to force material 6 upwardly in bore 8 and thereby propel piston 4 outwardly against the aforementioned spring. During temperature decrease in the atmosphere material 3 contracts so as to allow the spring to return piston 4 downwardly to its illustrated position.

For many applications it is desirable that material 3 have a relatively large total expansion. Such a large total expansion gives piston 4 a relatively long stroke per given size power element, or in the alternative permits a reduction in power element size required to effect a given piston movement.

Expansion material 3 in the illustrated embodiment is particularly chosen to give a relatively large total expansion. Material 3 includes a mixture of thermally applications, Serial No. 551,829, filed on compounds is preferably bromine or chlorine.

of 1, 2, 4, 5 tetrabromobenzene and 1, 2, 4, 5 tetra- 2,915,899 Patented Dec.- 8, 1959 ice expansible material and discrete particles of heat-conducting copper, preferably in a volume ratio of about expansible material and 25% copper. The copper particles are evenly dispersed throughout the expansible material so as to quickly and evenly conduct heat from the atmosphere through the expansible material and thereby cause piston 4 to be moved quickly in response to temperature change in the atmosphere.

The expansible materials of the present invention are solid aromatic or ring compounds of a symmetrical character, i.e. any substituted atom or radical at one position on a ring is balanced by one or more similar elements or radicals at opposite points on the ring. It has been found that the symmetrical nature of the chosen compounds permits the individual molecules to pack or fit close together in the solid state. As a result there are more molecules available for expansion during temperature increase, and the material therefore undergoes a relatively large total expansion.

The expansible material may be 1, 2, 4, 5 tetrahalo genated benzene or 1, 3, 5 trihalogenated benzene or 44 dihalogenated biphenyl or naphthalene or fiuorene. The halogen in the three above mentioned halogenated Mixtures chlorobenzene may be used to give expansion temperature ranges intermediate that of pure 1, 2, 4, 5 tetrabromobenzene and pure 1, 2, 4, 5 tetrachlorobenzene. Similarly mixtures of 1, 3, 5 tribromobenzene and 1, 3, 5 trichlorobenzene may be employed to give expansion temperature ranges intermediate that of pure tribromobenzene and pure trichlorobenzene. Combinations of dichlorobiphenyl and dibromobiphenyl may also be employed in a similar manner. In each case where a mixture of materials is employed the expansion temperature range will be determined according to the relative amounts of the component materials being employed.

In the foregoing specification the expansion materials have been described with reference to their use in power elements of the type which are responsive to ambient temperature changes. However it is also contemplated that the expansion materials can be employed in power elements of the type which are responsive to changes in electric current, as for example the power elements disclosed in aforementioned patent application, Serial No. 551,829. It will be understood therefore that the term power element as used herein, refers both to temperature responsive devices and electric current responsive devices.

We claim:

1. A thermally expansible pellet formed as a three dimensional body comprised of heat-conducting material dispersed within a solid expansion material transformable to a liquid in its operating range; said expansion material being selected from the group consisting of l, 2, 4, 5 tetrahalogenated benzene; l, 3, 5 trihalogenated benzene; 4-4 dihalogenated biphenyl; and fluorene.

2. The combination of claim 1 wherein the expansion material is l, 2, 4, 5 tetrabromobenzene and 1, 2, 4, 5 tetrachlorobenzene.

3. The combination of claim 1 wherein the expansion material is l, 2, 4, 5 tetrahalogenated benzene.

4. The combination of claim 1 wherein the expansion material is l, 3, 5 trihalogenated benzene.

5. The combination of claim 1 wherein the expansion material is 44 dibromobiphenyl.

6. The combination of claim 1 wherein the expansion material is fluorene.

(References on following page) 

1. THERMALLY EXPANSIBLE PELLET FORMED AS A THREE DIMENSIONAL BODY COMPRISED OF HEAT-CONDUCTING MATERIAL DISPERSED WITHIN A SOLID EXPANSION MATERIAL TRANSFORMABLE TO A LIQUID IN ITS OPERATING RANGE; SAID EXPANSION MATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF 